1. Field of the Invention
The present invention relates to a method and device for electrically detecting biomolecules.
2. Description of the Prior Art
Carbon nanotubes (CNTs) have a tremendous potential for a wide variety of applications due to their unique mechanical, electrical, and chemical characteristics. The CNTs have excellent characteristics such as extremely high electrical conductivity, high length-to-diameter ratio, and excellent structural strength. Thus, it is expected that CNTs can be used to produce new products that have unique properties compared with existing ones.
Single-walled carbon nanotubes (SWCNTs) have attracted attention as new nano-biosensor materials because of their high aspect ratios, excellent chemical, mechanical, and electrical characteristics. SWCNTs exhibit a pronounced change in their electrical characteristics even when reacted to a trace amount of biomolecules. Thus, SWCNT biosensors have been developed that can detect the change in the characteristics of the SWCNTs before and after the reaction to the biomolecules. In the case of most of the presently available biosensors using the SWCNTs, attempts have been made to detect biomolecules with field effect transistors (FETs) or Schottky barrier transistors. These methods generally have difficulties in immobilizing the probe on the surface of the SWCNTs, and are subjected to bonding between the SWCNTs and the biomolecules since the reaction occurs on the surface of a substrate. This bonding is inefficient, since the biomolecule has to be bonded to the SWCNT.
Further, there still exists a possibility of alteration in the characteristics of the SWCNT or the target biomolecules due to immobilization of the SWCNT on the surface of the biosensor, or immobilization of the target biomolecules on the surface of the SWCNT.
In cases where a non-electrical method is used to detect the biomolecules, fluorescent or other chemical labels are usually attached to the targets to be detected, and then signals generated from the labels are measured. In this case, a pre-treatment process such as labeling target samples is most often utilized and these processes are usually time-consuming, so that it is difficult to analyze various samples in a short time. Further, it is difficult to verify that the labels are attached only to the target biomolecules in the process of the labeling.
Thus, it is desirable to have a method and device capable of rapidly and accurately detecting the target biomolecules without any sample pre-treatment process such as the labeling or bonding.